retitle 474947 "fix Dynamic MMaps error"
severity 474947 important
tag 474947 -unreproducible
thanks

hi bug, hi people, hi d-release

I did some study on bug 474947, that is grave/RC, and is posted against APT.

Since I was told that the APT team is understaffed, I decided to take
action myself.

---

First of all, I tried to focus the problem.

In this same bug there were reported two different issues, a "Dynamic
MMap error"  and a segmentation fault; moreover some people were using
APT in Etch, and some other in Lenny.

Let's summarize it shortly.

First poster is Elliot Mitchel, in Apr 08; he is using APT 0.6.46 inside
Etch. He claims that he cannot work around a "Dynamic MMap" error; he
then sets severity to grave.
 It turns out that he is using the wrong option, he is using '-o
APT::Cache-File=200000000' instead of '-o APT::Cache-Limit=200000000' .
(And that confuses "Joe Nahmias" and me as well - the mistake is noted
by JackYF quite later). So the first report is flawed.

jasen reports a similar problem, but I don't see enough details to comment.

Then Elliott Mitchell again also posts a report about a segmentation fault.

Some months go by; in Sept. JackYF offers to help fixing the problem by
changing the code.
(Unfortunately we are already in deep freeze, and I am afraid deep
changes to APT would not be accepted by the release team.)

----

I did some more research around, and tests, and this is what I found out.

The default in APT (inside the code) for Cache-Limit in Lenny is 20MB ,
in Etch is 8MB .

Note also that in the Lenny release notes
http://svn.debian.org/viewsvn/ddp/manuals/branches/release-notes/lenny/en/upgrading.dbk
 it is suggested to set Cache-Limit to 12500000 in case of Dynamic MMap
error.


I tested APT 0.6.46 in Etch. I tried with 3 different sources.list, see
attachment. The "fat" list is the union of all lists of all reporters
(minus obsolete and duplicates).

The two smaller files work perfectly well; the "fat" sources file does
trigger the DynamicMMap problem, that I can though work around by using
 'apt-get -o APT::Cache-Limit=100000000 update'

The only way to trigger a segmentation fault was instead to set
Cache-Limit to a ridiculously low value.

So my conclusion is that the forthcoming release notes do address the
problem some people may encounter in upgrading from  Etch to Lenny.

I propose the attached patch, though, since it is funny to suggest a
value of 12500000 (bytes) when the internal value in Lenny is 20MB.
I hope someone in the d-relase team can apply it.

a.

Index: manuals/branches/release-notes/lenny/en/upgrading.dbk
===================================================================
--- manuals/branches/release-notes/lenny/en/upgrading.dbk	(revisione 5426)
+++ manuals/branches/release-notes/lenny/en/upgrading.dbk	(copia locale)
@@ -957,10 +957,11 @@
 to a value that should be sufficient for the upgrade:
 </para>
 <screen>
-# echo 'APT::Cache-Limit 12500000;' &gt;&gt; /etc/apt/apt.conf
+# echo 'APT::Cache-Limit 21000000;' &gt;&gt; /etc/apt/apt.conf
 </screen>
 <para>
-This assumes that you do not yet have this variable set in that file.
+This assumes that you do not yet have this variable set in that file;
+otherwise you may manually edit the file to set the above variable.
 </para>
 <para>
 Sometimes it's necessary to enable the <literal>APT::Force-LoopBreak</literal>

deb http://debian.oregonstate.edu/debian/ stable main contrib non-free
deb http://security.debian.org stable/updates main contrib non-free
deb http://www.debian-multimedia.org stable main
deb http://volatile.debian.org/debian-volatile stable/volatile main contrib 
non-free
deb http://debian.oregonstate.edu/debian/ testing main contrib non-free



deb-src http://debian.oregonstate.edu/debian/ stable main contrib non-free
deb-src http://security.debian.org stable/updates main contrib non-free
deb-src http://www.debian-multimedia.org stable main
deb-src http://volatile.debian.org/debian-volatile stable/volatile main contrib 
non-free
deb-src http://debian.oregonstate.edu/debian/ testing main contrib non-free


#---------

deb http://ftp.egr.msu.edu/debian/ unstable main contrib
deb-src http://ftp.egr.msu.edu/debian/ unstable main contrib

deb http://ftp.us.debian.org/debian/ unstable main contrib non-free
deb-src http://ftp.us.debian.org/debian/ unstable main contrib non-free


deb http://ftp.us.debian.org/debian/ etch main contrib non-free
deb http://ftp.us.debian.org/debian/ lenny main contrib non-free

deb-src http://mentors.debian.net/debian unstable main contrib

#------------
deb ftp://ftp.nz.debian.org/debian etch main non-free contrib
deb-src http://ftp.nz.debian.org/debian stable main non-free contrib
deb http://ftp.nz.debian.org/debian lenny main contrib non-free
deb http://ftp.nz.debian.org/debian unstable main contrib
deb http://www.debian-multimedia.org etch main


deb ftp://ftp.au.debian.org/debian etch main non-free contrib
deb-src http://ftp.au.debian.org/debian etch main non-free contrib

deb-src http://ftp.nz.debian.org/debian testing main contrib non-free

deb ftp://ftp.nerim.net/debian/ stable main contrib non-free


deb http://ftp.it.debian.org/debian/ etch main contrib non-free
deb-src http://ftp.it.debian.org/debian/ etch main contrib non-free

deb http://volatile.debian.net/debian-volatile etch/volatile main contrib 
non-free

deb http://security.debian.org/ etch/updates main contrib non-free
deb-src http://security.debian.org/ etch/updates main contrib non-free

deb http://www.debian-multimedia.org etch main


deb http://ftp.it.debian.org/debian/ lenny main contrib non-free
deb-src http://ftp.it.debian.org/debian/ lenny main contrib non-free
deb http://volatile.debian.net/debian-volatile lenny/volatile main contrib 
non-free
deb http://security.debian.org/ lenny/updates main contrib non-free

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